Thread chain severing device for sewing machines



g- 11, 1964 H. F. DANIEL ETAL 3,143,987

THREAD CHAIN SEVERING DEVICE FOR SEWING MACHINES Filed 001'.- 25, 1962 v 5 Sheets-Sheet 1 Flat.

Aug. 11, 1964 H. F. DANIEL ETAL 3,143,987

, THREAD 0mm SEVERING DEVICE FOR SEWING MACHINES Filed 001;. 25, 1962 Y s Sheets-Sheet 2 1964 H. F. DANIEL ETAL 3,143,987

THREAD CHAIN SEVERING DEVICE FOR SEWING MACHINES Filed Oct- 25, 1962 3 Sheets-Sheet 3 FIGJO.

FIGJ I.

United States Patent 3,143,987 TEAD HAIN SEVERING DEVICE FOR SEWING MACHHNES Hermann Ferdinand Daniel, Stuttgart, and Willi Ferdinand Wolfgang Niem, Beinstein, Kreis Waihlingen, Germany, assignors to Union Special Maschinenfabrik,

G.m.b.H., Stuttgart, Germany Filed Oct. 25, 1962, Ser. No. 233,085

Claims priority, application Germany Oct. 26, 1961 Claims. (Cl. 112-252) This invention relates to mechanism for cutting the thread chain formed between successive pieces of work fed through a sewing machine. It is provided with a suction tube so constructed and arranged in relation to the other portions of the machine as to insure the introduction of the thread chain properly into cooperation with the cutting devices of machines operating at high speeds.

The employment of means adapted to direct a thread chain into a cutting device by an airstream has previously been suggested. However, the means heretofore provided for this purpose have not functioned properly at times so that the thread chain between successive work pieces fed continuously through the stitch forming zone of the sewing machine has not always been properly severed, without damage to the work pieces and with a relatively short length of free thread extending from the work. The present invention serves to overcome the difficulties previously encountered with mechanisms heretofore suggested for the indicated purpose.

While attempts have been made to perform the desired severing operation automatically through the use of suction devices provided on sewing machines behind the stitch forming point and the thread severing cutters, the arrangement of the various parts has not been such as to insure proper drawing of the thread into the cutting device without the danger of having the edge of the material itself drawn into the cutting device and thus undesirably cut. Furthermore, prior devices suggested for the purposes of the present invention. have been of such character that it has been difficult to leave a thread of minimum length projecting from the work piece after the severing operation has been performed.

A primary object of the present invention has been to provide a thread chain cutting device which assures cutting of the thread in such a manner and at the proper time as to leave a minimum length of the end of the thread remaining attached to the work being sewn and to prevent any damage being done to the work being stitched.

To attain the foregoing objective, the present invention serves to provide a suction tube having its forward portion arranged parallel to the direction of advance of the material, the mouth or thread receiving end of the tube forming a guide surface disposed at an oblique angle to the direction of advance of the work. Any suitable means may be provided for creating a suction action or partial vacuum within the tube. The mouth end of the tube is provided with an opening that is spaced from the longitudinally extending wall of the tube. This opening is preferably arranged in direct alinement with the thread chain as the latter is formed forwardly of the trailing end of the work, i.e., between such trailing end and the stitch forming point. In machines provided with a stitch finger the opening referred tois preferably aligned with the stitch finger, with its center substantially in the plane of the top of the conventional throat place of the machine. Moreover, the opening which extends through the obliquely disposed end Wall of the tube has a slot extending therefrom to a point where the end wall merges into the surrounding Wall of the tube and longitudinally of the latter into the region in which the thread cutting device ice is provided. This arrangement is such that the work being stitched is deflected by the obliquely arranged guide surface mentioned to that portion of the surrounding wall of the suction tube adjacent which the cutting device is disposed, and then moves paarllel with that wall of the tube. In the course of such movement of the work, the thread chain extending from the trailing end of the Work is drawn inwardly into the interior of the tube by the suction action. This serves to dispose a portion of the thread chain at substantially a right angle to the line of advance of the work, and the severing of the thread is then performed upon this laterally extending portion of the thread chain. In a similar manner, the thread chain which extends outwardly from the forward end of the next work piece is drawn between the cutting blades as the forward end of such work piece passes along the suction tube in the region of the cutter. Thus a minimum length of thread is left at each end of the work piece.

As will be explained in connection with a detailed description of several embodiments of the invention, the cutting device which severs the thread chain may either be disposed within the suction tube or it may be provided along the outer surface of the latter. In the latter case, a work guiding member is provided parallel with the suction tube and spaced slightly from the latter. The thread cutting means is positioned adjacent the inner surface of this member.

A further feature of the preferred embodiment of the invention is the provision of an enlarged, hollow head at the downstream end of the suction tube which is adapted to enable the latter to be readily and quickly connected with a hose line which extends either from a vacuum producing device or from an air compressor. This arrangement is such that when the sewing machine embodying the thread chain cutting mechanism of the present invention is installed at a point where a suction line is available, this may readily be connected to the trimmer mechanism by a flexible hose line. On the other hand, if the place at which the machine is installed does not have a suction line readily available, then a compressed air line, which is almost always available, may be connected to the thread cutting unit. In this case, the arrangement is such that the compressed air delivered to the unit will be forced through a passage adapted to produce a Venturi action, thus imparting a partial vacuum or suction action within the suction tube. A hose line may then be connected to the discharge end of the special fitting to receive the thread clippings and deliver them to a suitable disposal point.

With the foregoing objects, features and advantages of the invention in view, several embodiments of the same will now be described in further detail by reference to the accompanying drawings, in which:

FIG. 1 is an elevational view of parts involved in the invention disposed in the region of stitch formation of a sewing machine of the overedge stitch forming type.

FIG. 2 is a view, partly in plan and partly in horizontal section, showing various elements of the construction illustrated in FIG. 1.

FIG. 3 is a vertical sectional view taken along the FIG, 8 is a vertical sectional view taken along the line 88. of FIG. 7.

FIG. 9 is a view similar to FIG. 8 but illustrating a modified form of thread severing means.

FIG. 10 is a sectional view through a portion of the suction tube of the trimmer mechanism and devices for readily connecting the, suction tube with suction producing means; and

FIG. 11 is a sectional View through a modified form of connection of the character shown in FIG. 10, adapting the system to be connected into an air pressure line rather than a suction line.

For simplicity of disclosure of the invention, the drawings illustrate very little of the structure of the sewing machine to which the invention is applied. It may be mentioned that the embodiments illustrated in FIGS. 1-5 are of types adapted to be used in connection with overedge sewing machines. A sewing machine of this character to which the invention may be readily applied is disclosed in the United States patent to Wallenberg et al. No. 2,704,042, granted Mar. 15, 1955. The devices illustrated in FIGS. 6-9 are adapted for application to flatbed sewing machines of types well known in the art. Typical of the numerous patents which illustrate flatbed machines to which the invention may be applied are the United States patents to Attwood No. 2,729,179, granted Jan. 3, 1956, and Attwood No. 2,780,192, granted Feb. 1957.

Turning now to FIGS. 1-3 of the drawings, there is illustrated a work support of an overedge sewing machine of the character mentioned above, a throat plate 11 being provided in the work support in the region of stitch formation. A presser foot 12 carried by a spring-urged arm1l3, serves to retain the work to be stitched against the surface of the throat plate. It will be understood that suitable stitch forming devices are provided adjacent to the presser foot for producing an overedge line of stitching in the work. Such stitch forming mechanism will include a needle 14(FIG. 2) and a looper or spreader 15 (FIG. 1). It will be understood that a second looper or a spreader will also be included in the stitch forming mechanism, as shown in the above-mentioned patent to Wallenberg et al. In the course of the operation of the machine the work is advanced by a plurality of feed dogs 17 and 18 which pass upwardly through suitable openings in the throat plate 11. In addition there is preferably provided a thread chain feeding dog 15, which is in alignment with a stitch finger or tongue 19 carried by the throat plate. The various feed dogs may be driven by suitable connections from the main drive shaft of the machine, such as illustrated in the Wallenberg et al. patent.

As has been indicated, the present invention is of particular utility in connection with machinesintended to operate upon a continuous succession of work pieces. As each work piece 20 is advanced through the stitch forming zone of the sewing machine, and carried beyond the latter, a thread chain 21 is formed that extends from the trailing end of the work piece that has been stitched to the leading end of the next following work piece. This thread chain is advanced toward the left (FIG. 2) by the feed dog 16. In alignment with the latter is a tubular member 22 which, as shown in FIG. 3, may suitably be square in cross section. Its forward end or face 23 extends vertically from a point below the throat plate 11 toa-point above the latter. As shown in FIG. 2, this face 23 is'inclined at an oblique angle to. the direction of movement of the work and the free thread-chain and serves to deflect and guide the stitched edge of the workas the. latter is advanced. It is provided adjacent its midpointwith an opening 24 into which the trailing thread chain may read ily be drawn by the suction created within thetube 22 as the work piece 20 continues its advance toward the left.

In spite of the deflection of the stitched edges of the work' pieces as theyreach the face 23, the trailing thread chain 21 is introduced into the interior of the suction tube 22 by virtue of the action of the suction thereon. To make this possible the face 23 of the suction tube and the longitudinal wall 25 thereof are provided with a slot 26 which extends from the opening 24 to a point at a suitable distance from the line along-which the face 23 merges into the wall 25; This slot has a vertical dimension suificient to enable the free passage of the thread chain therethrough and there along, but it is not suflicient to enable the edge of the work piece to pass through it. Accordingly, when the work piece reaches the position indicated in FIG. 2, the thread. chain willhave a portion extending axially of the suction tube 22 and another portion extending at substantially a right angle to the axis of the tube, outwardly through the slot 26 to the work piece. When the parts are in this position, the thread chain will be automatically severed by the action of a movable cutter blade 27 and a fixed cutter blade 28 which may form a portion of the front vertical wall of the suction tube in a region above the slot 26. The movable cutter blade 27 may be operated through any suitable connections from the drive shaft of the sewing machine adapted to reciprocate the movable blade upon each revolution of the drive shaft. For example, the movable blade may be secured to one or another ofthe pitmans I26 and 128 shown in the Wallenberg et al patent. These pitmans, it will be understood, are given a slight vertical movement upon each revolution of the main drive shaft of the machine to lift the feed dogs into engagement with the work, and this movement is sufficient to cause the cooperating edges of the two cutter blades to sever the thread chain. While the pitmans mentioned are also given a limited extent of longitudinal movement, this does not interfere with the proper cooperation of the cutter blades.

In FIGS. 4 and 5 there is shown a slightly modified form of the suction tube. As there shown, the tube 29 may be of circular cross section which is of smaller area than that of the tube 22'. Adjacent the forward end of tube 29 there is provided a guard member 30 having an obliquely disposed end portion 30a which substantially closes the adjacent end of the tube 29 which is similarly disposed at an oblique angle. An openingis provided through the center of the portion 30a, which is aligned with the stitch tongue 19 and the chain feed dog 16. This opening is disposed at the same level as the top of the throat plate 11. From the opening in the portion 349:: there is provided a slot, similar to the slot 26, which has its lower surface in the plane of' the top of the throat plate 11. This slot is indicated at 3011 in FIG. 5. Above the slot is provided, either integrally with the member 30 or as a separate element secured thereto, a small plate 31 having its lower edge adapted to provide the fixed cutting edge. The movable cutter blade 32, similar to blade 27 of FIG. 1, is slidablevertically along the inner face of themember 30.. Cutter blade 32 may be connected for movement upon each revolution of the main drive shaft of. the machine in the same manner as the blade' 27. Horizontally aligned with the slot 30b in member 30, thereis provided a corresponding slot 29a through the wall of tube 29. It will be seen that this arrangement permits the free thread chain to extend longitudinally along the center of the tube 29 and have a portion extending outwardly at right angles through the slots 29a and 30b. Thus, whenever the trailing end of a work piece'reaches the zone of action of the blades 31 and 32, the transversely extending portion of the thread chain will be neatly severed, with a minimum of length of thread remaining attached to the work piece, and without danger of cutting the edge of the work. The remaining free thread is suckedback into the tube 29 and becomes attached to the leading end of the next work piece. When such leading end is deflected by member 30, the adjacent portion of the thread chain will be drawn through the slots 2% and 30b and will be brought into cooperation with the cutter blades to free the thread chain for delivery by the suction action, to a suitable disposal point. Thus the thread chain attached to the work, at both the leading and trailing ends thereof Will be held to aminirnum.

Referring now to FIGS. 6-9, there is shown a form of the invention adapted for use in connection with a flatbed machine. Only the presser foot 33 and the throat plate 34 of such a machine are illustrated, but it will be understood that suitable mechanism will be provided in the machine for forming a desired line of stitching in a succession of work pieces, with a free thread chain formed between successive work pieces.

As the work piece advances beyond the stitch forming zone, in the region of the presser foot, it is advanced upwardly along the inclined surface 35a of a supporting plate 35 which, in cross section, may have the form illustrated in FIG. 8. In alignment with the thread chain being advanced along the surface of the throat plate, there is provided an opening 36 in the portion 35a of member 35, the center of said opening being in the plane of the top surface of the throat plate. This opening is aligned with a suction tube 38 and communicates with a slot 38a in the wall of the suction tube through which a portion of the thread chain adjacent to the trailing end of the work piece may extend downwardly into the suction tube 38. The slot 38a is aligned with a similar slot 37 in the member 35 to permit this downward extension of the thread. Suction tube 38, it will be understood, is connected with any suitable vacuum producing means which serves to draw the thread chain downwardly into the tube and then longitudinally of the axis of the tube. That portion of the thread chain which is directed vertically by the connection with the trailing end of the work piece, passes between the cutting edges of a stationary blade 39 and a movable blade 40. The latter may be connected in any suitable way with the drive shaft of the sewing machine for causing it to reciprocate in the directions indicated by the arrows in FIG. 8. Thus, it may be seen that the advantages described in connection with the other embodiments of the invention, will be derived from this construction.

. FIG. 9 shows a modification of the structure shown in FIGS. 6-8 in which the thread severing means is in the form of an incandescent wire 41, which may be connected with a source of electricity in any convenient manner. This arrangement is such that as the free thread chain passes through the slot 37 from the trailing or the leading end of the work piece, it will be brought into engagement with the incandescent wire and will be quickly severed. This is of particular utility in connection with sewing machines utilizing plastic threads to form seams. While this incandescent wire, thread-severing means has been disclosed in connection with a flatbed machine, it may also be used in connection with an overedge machine. Thus the cutter blades shown in FIGS. 1-5 may be replaced by incandescent wire, thread-severing means.

In FIG. there is illustrated a preferred arrangement for connecting the suction tube of the thread chain cutter with a vacuum pump for establishing the desired suction. This may be employed in connection with any of the forms of the invention described above. The suction tube is indicated at 42, and this may either be of the square or rectangular, cross-sectional form shown in FIGS. 1-3, or of the circular cross-section, cylindrical form shown in FIGS. 4 and 5. Of course the crosssection of the suction tube may be of any other suitable configuration.

At the end of the suction tube 42, remote from that at which the thread severing devices are provided, there is secured a bell-shaped fitting 43. This may be welded or otherwise secured to the suction tube 42. The enlarged portion of fitting 43 has a sloping or tapering surface 43a, preferably of frustro-conical form. This is adapted to receive a connecting member 44 having an outer surface portion 44a of substantially the same frustro-conical form, adapted to be snugly received within fitting 43 by simply introducing the member 44 longitudinally into the fitting. At its outer end, the member 44 is provided with a reduced diameter portion 44b, the outer surface of which is preferably grooved. A flexible tube or hose line 45 is adapted to be connected with the portion 44b of member 44, and it may be firmly retained thereon, if desired, by clamping it through the use of wire or the like serving to press the flexible tube into the grooves of portion 44b. It will be understood that the flexible hose line 45 is connected at its opposite end with a vacuum producing pump.

FIG. 11 discloses a modified form of the connecting member shown in FIG. 10, which adapts the suction tube 42 to be connected into a compressed air line rather than a suction line. For this purpose, the suction tube 42 carries the same type of bell-shaped head 43 as described above. It also embodies a connector member 44 which is of the same form as that described in connection with FIG. 10, except that it has an opening through the sidewall thereof to receive a fitting to be described. Within the enlarged portion of member 44 there is mounted an element 46, a portion of which is snugly fitted, in airtight relation, within the righthand portion of member 44, as shown in FIG. 11. The element 46 has a central bore 46a aligned with the suction tube 42. As shown, this bore is slightly enlarged into frustro-conical form at its righthand end. Element 46 has a reduced diameter portion which provides an annular chamber 46b between the outer surface of element 46 and the inner surface of member 44. It is in the region of this annular chamber that the wall of the member 44 is provided with an opening to permit the insertion and retention of a nipple 47. This nipple, which has a bore extending through the same has its outer surface grooved in the manner explained in relation to part 441), for the reception and retention of a flexible hose 48, the opposite of which is connected into a source of air under pressure.

Toward the left (FIG. 11) of the annular chamber 46b, the element 46 has an extension provided with a frusto-conical surface 460. The inclination of this surface to the axis of element 46 is slightly less than the inclination of an opposed inner surface on a portion of member 44. This arrangement is such that as air under pressure is introduced into the annular chamber 46b its velocity of movement will increase as it advances toward the lefthand end of the element 46, thus producing a Venturi action that creates a suction effect within the passage 46a. Preferably, as shown, the lefthand end of the passage 46a is of slightly reduced diameter, as indicated at 46d. The air thus drawn from the suction tube 42 through the passage 46a will be merged into the high velocity compressed air discharging from chamber 46b. The combined air and severed thread sections will be discharged from the member 44 into a flexible hose line 49 secured to the portion 44b of member 44. Hose line 49 may discharge into any suitable receptacle for the accumulation of the severed thread sections. This is a highly advantageous arrangement since it simplifies the disposal of the severed thread sections. The latter may pass through to a receptacle unimpeded by obstructing surfaces.

While the invention has been shown and described in relation to single thread chain producing sewing machines, it may readily be adapted for the severing of a plurality of thread chains produced by a multiple-needle sewing machine in which individual rows of stitches are formed. For this purpose a plurality of cutting devices of the character described above may be provided alongside of each other. This is in the event that the needle spacing is relatively large. However, a single suction tube having a wide mouth with a plurality of suction openings and having a plurality of thread chain severing devices, one aligned with each of the openings, may be employed.

Alternatively, particularly where the needle spacing is not great, one pair of cutting knives may be employed, these having a plurality of cutting edges, one positioned in spaced'alignment with each of the suctionopenings that are, in turn, aligned withthe paths of movement of the thread chains. severing means may be in the form of an incandescent wire, across which all of the thread chains are drawn by the suction action at the appropriate times.

As has been stated, the slot in the suction tube or a guide plate which permits the passage of the thread chain into engagement with the thread severing means should not be wide enough to permitthe entry of the edge of the work, when the invention is applied to an overedge sewing machine. This is not necessary when the invention is applied to flatbed machines, as shown in FIGS. 6-9, since the flat face of the work, rather than its edge, is carried over and along the slot. t is simply necessary to have the slot sufiiciently narrow not to permit the suction to cause folding or bending of the fabric in a way to carry a portion of it into the path of the thread severing means.

With respect to the connecting means shown in FIGS. 10 and 11, it is not necessary that the cooperating portions of the parts 43, 44 and 46 be of circular cross section. They may have any other cross sectional configuration which will enable the sliding, close fitting cooperation of various surfaces and the other relationships required in the FIG. 11 embodiment. If it is desired to provide a single, standard connecting unit, adapted to connect the suction tube into either a vacuum or an air pressure line, the form shown in FIG. 11 may be adopted. In this event, when the unit is to be used to tie into a vacuum line, the bore of the fitting 47 may be closed by a plug, or the fitting 47 may be removed and the opening through the wall of member 44 which receives the fitting may be closed by a plug.

Other modifications in or embodiments of thread chain cutting means produced in accordance with the invention, may be made within the scope of the appended claims.

What is claimed is:

1. In a sewing machine, means adapted to form a chain of thread between successive work pieces fed through the stitch forming mechanism of the machine, an enclosed tubular member in alinement with the chain of thread as the latter is formed by said means adapted to have a suction created in its interior and adapted to have the chains of thread formed between successive work pieces drawn into the member by suction, closure means at the inlet end of said member provided with an obliquely inclined surface, the inclined surface merging into a surface extending longitudinally of said member, said closure means having an opening extending therethrough in alinement with said chain forming means and said chain of thread as the latter is formed, said opening being of suflicient size to permit the chain of thread to pass therethrough into said member, a narrow passageway extending from said opening in said closure means to said surface extending longitudinally of said member In lieu of cutting knives, the thread and for a limited distance along said member, thereby enabling a portion of a thread'chain attached to a work piece to travel along said passageway, and thread severing means disposed between said surfaceextending longitudinally of said member and the longitudinal axis of said member for severingthe thread chain at apoint' adjacent that at which the thread chain extends from the work piece towardthe longitudinal axis of said member as a result of the suction within said member.

2. In a structure of the character set forth in claim 1, said surface extending longitudinally of said member being provided on said member-, and said thread severing means being provided within said member.

3. Ina structure of the'character set forth in claim 2, said thre'adsevering meanscornprising a stationary blade forming a part of the wall of said member and a movable blade. within said member coacting with said stationary blade.

4. In a structure of the character set forth in claim 1, said surface extending longitudinally of said member being spaced slightly outwardly thereof on an extension of said member being a relatively small diameter tube, and

said severing. means comprising afixed blade carried by said extension of said closure means and a blade movable horizontally between said fixed blade and saidtube across the path of the thread extending from the work piece 7 to the interior. of said tube. 1

7. In a structure of the character set forth in claim 1, said thread severing means being an incandescent wire.

8. In a. structure of the character set forth in claim 4, said thread severing means being an incandescent wire.

9.v In a structure of. the'character set forth in claim 4, said passageway being formed by aligned narrow slits extending longitudinally of said member and said extension of said closure means.

10. In a structure of the character set'forth in claim 1, said sewing machinev having a throat plate over which the work pieces. are passed as they are being stitched, said passageway for the thread being a slit the lower end of which is in the plane of the top of said throat plate.

References Cited in the file of this patent UNITED STATES PATENTS 2,607,101 Stout Aug. 19, 1952 2,989,935 Butler June 25, 1961 3,008,437 Herr Nov. 14, 1961 3,058,438 Russell et a1. Oct. 16, 1962 

1. IN A SEWING MACHINE, MEANS ADAPTED TO FORM A CHAIN OF THREAD BETWEEN SUCCESSIVE WORK PIECES FED THROUGH THE STITCH FORMING MECHANISM OF THE MACHINE, AN ENCLOSED TUBULAR MEMBER IN ALINEMENT WITH THE CHAIN OF THREAD AS THE LATTER IS FORMED BY SAID MEANS ADAPTED TO HAVE A SUCTION CREATED IN ITS INTERIOR AND ADAPTED TO HAVE THE CHAINS OF THREAD FORMED BETWEEN SUCCESSIVE WORK PIECES DRAWN INTO THE MEMBER BY SUCTION, CLOSURE MEANS AT THE INLET END OF SAID MEMBER PROVIDED WITH AN OBLIQUELY INCLINED SURFACE, THE INCLINED SURFACE MERGING INTO A SURFACE EXTENDING LONGITUDINALLY OF SAID MEMBER, SAID CLOSURE MEANS HAVING AN OPENING EXTENDING THERETHROUGH IN ALINEMENT WITH SAID CHAIN FORMING MEANS AND SAID CHAIN OF THREAD AS THE LATTER IS FORMED, SAID OPENING BEING OF SUFFICIENT SIZE TO PERMIT THE CHAIN OF THREAD TO PASS THERETHROUGH INTO SAID MEMBER, A NARROW PASSAGEWAY EXTENDING FROM SAID OPENING IN SAID CLOSURE MEANS TO SAID SURFACE EXTENDING LONGITUDINALLY OF SAID MEMBER AND FOR A LIMITED DISTANCE ALONG SAID MEMBER, THEREBY ENABLING A PORTION OF A THREAD CHAIN ATTACHED TO A WORK PIECE TO TRAVEL ALONG SAID PASSAGEWAY, AND THREAD SEVERING MEANS DISPOSED BETWEEN SAID SURFACE EXTENDING LONGITUDINALLY OF SAID MEMBER AND THE LONGITUDINAL AXIS OF SAID MEMBER FOR SEVERING THE THREAD CHAIN AT A POINT ADJACENT THAT AT WHICH THE THREAD CHAIN EXTENDS FROM THE WORK PIECE TOWARD THE LONGITUDINAL AXIS OF SAID MEMBER AS A RESULT OF THE SUCTION WITHIN SAID MEMBER. 